Gasoline composition



United States Patent Office 3,052,528 Patented Sept. 4., 1962 3,052,528 GASOLINE CGMPOSITKON Douglas Graeme Roddick and Lawrence Bruce Scott, Lafayette, Calif, assignors to Shell Oil Company, New York, N.Y., a corporation of Delaware N Drawing. Filed July 1, 1958, Ser. No. 745,837 17 Claims. (Cl. 44-56) This invention relates to an improved gasoline composition for spark ignition internal combustion engines, especially for such engines having high compression ratios.

Since spark ignition engines were first manufactured the compression ratios of the engines have steadily been raised, especially in aviation and automotive engines. This has made possible greater power for the same size engine and more efficient utilization of the gasoline fuel. Increased compression ratios of course necessitated the use of fuels of increased resistance to detonation, or spark knock, but heretofore it has been possible, by the development of new hydrocarbon conversion processes for example cracking and reforming, and by using antiknock agents such as tetraethyl lead, to manufacture high quality fuels fully adequate to take advantage of advances in engine design.

Of the many aspects of gasoline performance (such as ease of starting, vapor-locking tendency, cleanliness, odor, combustion noise and the like) which the manufacturer of gasoline must consider carefully, the control of combustion noise is probably the most important because it indicates a reduced etficiency in utilizing available fuel energy and a resulting loss of power and mileage. In the past control of combustion noise has been primarily a matter of suppressing spark knock, but the compression ratios of the newer engines have reached a point where other related phenomena have become serious. Wild ping, a sharp engine noise something like the noise of spark knock but randomly occurring, is likely if the deposits in the combustion chamber tend to glow and ignite the fuel mixture prematurely. Even less familiar problems now becoming prevalent include pounding or high speed rumble, and hot starting.

Pounding is an engine noise which has been described as sounding like a broom handle dragged along a picket fence. It is encountered especially in the case of high compression engines, usually at fairly high speeds under moderate to heavy loads, and, like spark knock, is aggravated by increasing the compression ratio of the engine. Unlike spark knock however, raising the octane number of the gasoline will not prevent pounding. Precision measurements of high frequency combustion chamber pressure fluctuations have shown that pounding noise is not due to these as are the noises of spark knock and wild ping; analyses of pounding noise have shown that it involves high intensity sound in the low frequencies, especially in the 400 to 1500 cycles per second range, as compared to spark knock which is characterized by high intensity sound in the 6000 cycles per second range as well as a somewhat lesser intensity sound at about 600 cycles per second. It is possible that pounding is a vibration of power train components such as connecting rods, crankshafts and the like caused by excessive rise in pressure during the combustion of the fuel, i.e., too rapid a burning rate. It has been found that pounding is aggravated by increasing the concentration of aromatic hydrocarbons in the gasoline; this makes it likely that it will be a problem of increasing seriousness because the trend in refining processes has been toward gradually increasing concentrations of aromatics in gasoline.

Hot starting is another phenomenon which has been encountered only in the newer very high compression engines. This is a noise like spark knock which occurs when restarting a warm engine. Engine block and compression heat, the presence of deposits, the slow piston travel during cranking, and the susceptibility of the gasoline to spontaneous ignition all bring about an untimely ignition of the fuel mixture under such conditions that the fuel mixture detonates.

Many gasoline quality characteristics besides the avoidance of combustion irregularities have also recently become more critical. For example the gasoline should have a minimum tendency to form deposits not only in the combustion chamber but also in the fuel system. The carburetor and intake manifold in particular are critical in this respect because there the gasoline-air mixture is subjected to relatively high temperatures after the engine has been operated for some time and gums and resins are prone to form and interfere with the free flow of the fuel mixture and with the operation of the intake valves. This problem has been aggravated of late by the low profiles of the newer automobiles and the additional accessories in the engine compartment, such as air conditioning systems, which have considerably raised the normal engine compartment operating temperatures. 7

Still another important characteristic of gasoline is the extent of its tendency to develop static electrical charges during handling and the resulting likelihood that a spark discharge will occur. The extreme danger of this can largely be avoided if the gasoline will conduct electricity to a substantial extent whereby the charges are dissipated to ground.

These problems of course are by no means all that the manufacturer of gasoline must overcome. However, it is evident that they are among the more important ones and a gasoline improved in a number of these respects would be highly desirable.

It is a principal object of the invention to provide such a gasoline composition. It is a more particular object of the invention to provide a gasoline composition having performance characteristics such that abnormal combustion noise during its use in a spark ignition internal combustion engine is minimized throughout the entire operating range of the engine. Another object of the invention is to provide a gasoline composition having a lessened tendency to leave gums, resins and other deposits in the engine, especially in the fuel system. Still another object of the invention is to provide a gasoline composition having a reduced tendency to develop static electrical charges. Other objects will be apparent in the description of the invention.

In probably the last 20 to 30 years commercial gasoline has been composed of almost exclusively hydrocarbon components insofar as the energy-producing constituents are concerned. In the very early days of the use of spark ignition internal combustion engines alcohols were occasionally used as fuels; these were expensive and largely unsatisfactory in performance and were soon almost entirely abandoned in favor of hydrocarbon gasolines. During World War II branched alkyl ethers were proposed as high octane number components for aviation gasoline but they were not used on either a military or commercial scale. However, it has now been discovered that certain concentrations of a class of branched chain lower-alkyl ethers are surprisingly advantageous for practical use in hydrocarbon-base gasoline especially for automotive engines when used in conjunction with certain concentrations of a particular class of organic phosphorus compounds. In particular it has been found that when important concentration relationships are observed such ethers and such phosphorus compounds cooperate in a surprising way to provide a fuel having greatly improved 'quality characteristics in the respects described above.

Because abnormal combustion in modern very high compression gasoline engines has become so complicated it has been necessary to evaluate any given fuel proposed for commercial use on the basis of some all-inclusive criterion which will insure customer satisfaction with the fuel. An especially straight forward measurement of the adequacy of gasoline in these engines is the noise limited power obtainable from an engine operated on the fuel in question. As explained above irregularities in combustion are evidenced by noises quite different from those of normal combustion. It is extremely diflicult, however, to distinguish between the different kinds of combustion irregularities and in the final analysis it really does not make much difierence exactly how combustion is deviating from the normalit is the fact that it is which is important. The operator of an automobile is, of course, justified in caring only for maximum power and economy Without encountering any noises symptomatic of inadequacy of the fuel. A simple and direct way of judging the quality of the gasoline in respect to eflicient combustion is therefore to operate the engine at a given speed under gradually increasing load and gradually increasing throttle opening until abnormal combustion noises are encountered. This is almost exactly how in practice the operator of an automobile evaluates the quality of the fuel he is using, for example, in climbing a hill the operator will gradually open the throttle as far as possible until a combustion noise is detected, at which time he will close the throttle a bit until the noise stops. With a high quality fuel no noise may be encountered at all even at wide open throttle; in this case the power extracted from the fuel is the maximum possible for this engine in its particular mechanical condition.

The benefits of this invention are strikingly illustrated by this technique. A large number of gasoline blends have thus been evaluated in recent model automobiles having engines of 9.5 to 10.5 compression ratio. It was found that at 2500 rpm. engine speed, for example, and using a base hydrocarbon gasoline having a road octane number (Modified Uniontown) of 98-100 and containing 2-3 cc. TEL per gallon, the noise limited power was, after equilibrium engine deposits had been formed, about 35-50 brake horsepower (B.H.P.) at the rear wheels of the automobile. Adding enough diisopropyl ether or methyl tertiarybutyl ether to this gasoline to raise the road octane number by 1 to 2 numbers, for example 5 to by volume, and again operating the engine from clean condition to equilibrium combustion chamber deposits quite surprisingly did not increase the noise limtied power obtained as compared with the base gasooline. However, the addition of tricresyl phosphate, for example, to this base gasoline without any ether, in a concentration of from about 0.1 to about 0.4 theory very substantially raised the noise limited power obtained in these tests. Tricresyl phosphate at 0.3 theory in particular raised the noise limited power of the base gasoline to the range of 75 to 80 B.H.P. It is possible that this benefit was because in the tests with the base gasoline and the base plus ether the engine was limited, after equilibrium deposit had been built up, not by ordinary spark knock but by deposit phenomena. Now when both tricresyl phosphate and a branched chain lower alkyl ether, e. g., diisopropyl ether or methyl tertiarybutyl ether, was added to the base gasoline, for example at the same concentration of the ether again to raise the road octane number of the gasoline by one or two numbers, and at 0.3 theory of tricresyl phosphate (which of course does not in itself change the octane number of gasoline at all), it was found that the noise limited power was raised to the range 85 to 90 B.H.P. Thus it can be seen that while the ether did no good at all by itself under these conditions, in the presence of phosphorus it had a substantial benefit over and above the benefits obtained from the phosphorus compound alone.

Adding to the base gasoline a sufficient quantity of a high octane number hydrocarbon (together with a phosphorus compound) to raise the octane number to the same extent does not produce such a high quality of fuel. For example, when an aromatic compound is added the quantity of carbon-containing deposit in the combustion chamber increases leading to a greater tendency towards surface ignition, i.e. wild ping and the gasoline also has a much greater tendency to cause pounding. On the other hand, adding an isoparatfinic material such as aviation alkylate or the like aggravates the hot starting problem. This is not difiicult to understand because, as described above, hot starting noise is caused by the spontaneous ignition and detonation of the fuel when compressed under warm engine starting conditions. It therefore involves a diesel effect and it is well known that aliphatic hydrocarbons are highly susceptible to spontaneous ignition, which of course is why they are favored components of diesel fuel. Adding high octane (research method) olefins would seriously increase the gasolines sensitivity, leading to high speed and/or part throttle spark knock, while the branched chain lower-alkyl ethers have very low sensitivities and alleviate rather than ag gravate these problems.

A most interesting aspect of the composition of the invention is that the ether and the phosphorus compound cooperate to provide improved engine cleanliness and distribution of the gasoline heavy ends and relatively non-volatile additives among the cylinders. The phosphorus compounds in question have boiling points which are relatively high compared with the average of the gasoline as a whole; moreover, their viscosities are relatively high and in fact several of them are commercially used as plasticizers, for example tricresyl phosphate. On the other hand, the ether component is a better solvent for gums and other resinous deposits encountered in internal combustion engines than are the conventional hydrocarbon components, especially the non-aromatic ones, of the gasoline; this is probably because of the oxygenated character of both the gums and ethers. When a gasoline engine operated with the present gasoline composition is started the intake manifold is usually relatively cool and a substantial quantity of the ethers, even though they are relatively volatile, will appear in a liquid phase of gasoline on the walls of the intake manifold. The phosphorus compound softens or plasticizes any existing deposit making it easier for the ether to pull the deposits into the liquid whereby they are carried through to the combustion chamber where they are burned. Subsequently-formed deposits which may occur during an extended operation of the engine at normal operating temperatures are then taken into solution during the next warm up cycle of the engine.

The improved distribution effect of the combination of ether and phosphorus compound is brought about by the increased tendency of the liquid phase of heavy ends of the gasoline to creep along the walls of the intake manifold toward the combustion chambers. As the gasolineair mixture leaves the carburetor and enters the intake manifold it is, of course, partly in vapor form and partly in the form of dispersed liquid droplets. A substantial proportion of these liquid droplets collect as a liquid phase on the walls of the intake manifold. As this liquid phase moves toward the combustion chambers the lighter ends therein continue to evaporate. The relatively non volatile phosphorus compound of the composition of the invention has a higher surface tension than does the bulk gasoline and the relatively volatile ether has a lower surface tension than does the bulk gasoline; there is therefore a positive surface tension gradient in the direction from the carburetor to the combustion chambers. It has been found that under such circumstances a liquid phase will have a tendency to creep against the force of gravity; a commonly observed example of this phenomenon is the creeping of alcohol upwards along the vertical walls of wine glasses. The extent of the forces pulling the liquid film against gravity are directly proportional to the difference in the surface tensions of the components evaporating from the liquid film and the heavy ends left behind. The ethers of the present class have generally much lower surface tensions than gasoline hyrocarbons for example, the surface tension of diisopropyl ether at 25 C. is 17.3 dynes/cm. (Vogel, AL, J. Chem. 800., Part I, 616 (1948), as compared to about 26 dynes/cm. for gasoline hydrocarbons. Thus, the addition of both the ether and the phosphorus compound to gasoline hydrocarbons very substantially increases the surface tension gradient of the liquid along the walls of the intake manifold and thus increases its mobility, resulting in better distribution of the gasoline heavy ends and low volatility additives among the cylinders.

The gasoline compositions of the invention have still another attribute of importance. This is their surprisingly low tendency to develop electrostatic charges. It is of course known that the danger of electrostatic charging can be reduced by incorporating in hydrocarbon liquids additives which increase the electrical conductivity of the liquid. Additives such as the chromium salt of C alkylsalicylic acids are known to be especially effective. It has been discovered that the ethers and phosphorus compounds of the present gasoline composition, which are unlike anything known to have been suggested before for this purpose, cooperate in an unexpected fashion to increase the electrical conductivity of gasoline. For example a base gasoline containing only gasoline boiling range hydrocarbons was measured and found to have an electrical conductivity of 17 ohmcmr The addition of 3 cc. of tetraethyl lead per gallon to this base gasoline made very little difference; the conductivity was l5 10 ohmcmr Adding 0.3 grams of tricresyl phosphate per gallon to the base gasoline also made little difference; the conductivity was 19 10 ohm- CHI-1. The addition of 10% by volume of diisopropyl ether to the base gasoline increased the conductivity to some extent, i.e., to 27 10 ohmcmr However adding these same concentrations of tricresyl phosphate and diisopropyl ether together to the base gasoline more than doubled the electrical conductivity, i.e. raised it to 37 l0 ohnr emfand the addition of these same concentrations of tricresyl phosphate, diisopropyl ether and tetraethyl lead to the base gasoline about doubled its conductivity, i.e. raised it to 33x10 ohmcm.-

It is critical for the purposes of the invention that a proper selection of concentrations of both the ether and phosphorus compound be made. The concentration of ether must be at least 2% by volume and preferably at least 4% by volume. Ether concentrations of more than 50% by volume are not only usually unnecessary but would be deleterious in a number of respects. It is preferred that no more than 25% and especially no more than 17% by Volume of the ether be present in the gasoline composition. Especially preferred ether concentrations are from about 6 to by volume. The phosphorus compound should be present at a concentration of at least 0.001% by weight and no more than 0.1% by weight. It is preferred that at least 0.01% by weight of the phosphorus compound be present. It is also preferred that no more than 0.06% by Weight be present. Moreover, in addition to these weight limitations to the concentration of the phosphorus compound it is critical for the purposes of the invention that Where a lead antiknock agent such as a tetraalkyl lead, e.g. tetraethyl lead, is present, the concentration of the phosphorus compound is no less than 0.05 theory and no more than 0.6 theory. Preferred theory concentrations for the phosphorus compound are at least 0.2 theory and no more than 0.4 theory. In this connection it should be noted that one theory as the term is used herein referring to a phosphorus compound designates the amount of phosphorus compound stoichiometrically equivalent with the lead in the lead antiknock agent all of the lead atoms and all of the phosphorus atoms are present in the same proportion as in the compound Pb (PO- Thus in a given composition containing a lead anti-knock compound and a phosphorus compound, where T =theories of the phosphorus compound present, M =the number of gram mols of the phosphorus compound present, and A =the number of gram atoms of lead in the lead anti-detonant present:

The suitable ethers for practice of the invention are the branched chain di-lower-alkyl ethers containing a single oxygen atom, and at least 4 and no more than 8 carbon atoms, more especially 5 to 6 carbon atoms. Ethers outside this range are not only not useful in the present compositions but are, on the contrary, quite deleterious. For example dialkyl ethers which do not contain at least one branched chain alkyl group have such low octane numbers that their incorporation into gasoline, even in very small concentrations, could not be tolerated for use in modern high compression engines. Moreover, ethers containing either less or more carbon atoms would not have suitable volatility to accomplish the purposes of the invention. At least one, and preferably both, of the two carbon atoms attached to the single oxygen atom of the ether should preferably be a secondary or a tertiary carbon atom. Within the preferred class of branched chain dialkyl ethers having 5 to 6 carbon atoms, methyl tertiarybutyl ether, and especially diisopropyl ether are superior. Other suitable ethers within the scope of the invention include ethyl tertiarybutyl ether, isopropyl, secondary butyl ether, isopropyl, tertiarybutyl ether, methyl tertiaryamyl ether, ethyl isopropyl ether, methyl secondary b-utyl ether and methyl tertiaryhexyl ether.

An especially suitable ether component for the composition of the invention is a commercial diisopropyl ether product containing a minor amount of isopropyl alcohol and obtained by the reaction of propylene and water in a sulfuric acid medium, for example in accordance with the processes disclosed in Francis, U.S. 2,055,- 720, or in Oldershaw, US. 2,178,186. A typical product will contain a high concentration of diisopropyl ether, a smaller but substantial concentration of isopropyl alcohol, small concentrations each of ethyl isopropyl ether, ethyl alcohol, C to C propylene polymer, water and in some cases minute amounts of C to C hydrocarbons. The following are analyses of specific compositions which exemplify such suitable ether products:

present, i.e., so that Percent by weight B C D Diisopropyl ether 9 Isopropyl alcohol Ethyl isopropyl ether. Ethyl alcohol The organic phosphorus compound or mixture of compounds suitable for use in the gasoline composition of the invention must be hydrocarbon soluble and preferably contains only one phosphorus atom per molecule; it can be a phosphine, phosphine oxide, phosphite, phosphonite, phosphinite, phosphate, phosphonate, phosphinate or a sulfur analogue thereof. The organic radical or radicals of the phosphorus compound can be alkyl (acyclic or alicyclic) or aryl. They are preferably bydrocarbyl radicals (that is, radicals containing only carbon and hydrogen atoms) and especially cyclic hydrocarbon radicals. However, if desired, any radical may also contain a halogen atom, in which case the halogen atom is preferably chlorine or bromine, and especially chlorine. Of the cyclic radicals, hydrocarbyl-substituted cyclic radicals are preferred. Phosphorus compounds having only radicals containing up to car-hon atoms are most useful, and it is preferred that at least one and preferably all the radicals contain at least 4, and especially at least 6 carbon atoms. It is also preferred that the phosphorus compound contain no sulfur. Particularly suitable are the trihydrocarbyl phosphates, trihydrocarbyl phosphites and trihydrocarbyl phosphines.

Thus, suitable phosphorus compounds for the practice of the invention are those having the formula:

X is an oxygen or sulfur atom, that is, a chalcogen atom having an atomic number from 8 to 16, inclusive;

R is a monovalent radical containing no atoms other than carbon, hydrogen, and halogen, no more than one halogen atom, and from 1 to 10 carbon atoms;

a is a whole number from 0 to 1, inclusive;

b and c are Whole numbers from 0 to 3, inclusive, the sum of b and 0 being equal to 3.

Typically suitable for the purposes of the invention are the following exemplary compounds: tricresyl phosphate, tributyl phosphate, tributyl phosphite, diphenyl cresyl phosphate, triphenyl phosphate, octyl diphenyl phosphate, triamyl thionophosphate, triphenyl phosphine, trimethyl phosphine oxide, tris(2-propyl) phosphite, bis(Z-propyl) 2-propylphosphonate, trimethyl phosphate, trimethyl phosphite, phenyl dimethylphosphinate, propyl dicresyl thiolophosphate, tris(3,3,S-trimethylcyclohexyl) phosphate, tris(2-chloroprop-yl) thionophosphate, diphenyl cresylphosphonite, dimethyl xylyl phosphate, dimethyl cresyl phosphate, ethyl dimethylthiophosphinite, dimethyl phenyl phosphate and dimethyl phenylphosphonate.

The gasoline composition is most useful as fuel for automotive internal combustion spark ignition engines and as such the hydrocarbon components which comprise the major bulk of the gasoline can be straight run, thermally or catalytically cracked, thermally or catalytically reformed, or products of sulfuric acid or hydrofluor'ic acid alkylation of lower molecular weight olefins and isoparaifins, e.g. of butylenes and isobutane. Of course mixtures of such components are especially suitable. Automotive gasoline hydrocarbons have a boiling range of from about the boiling points of C to C hydrocarbons to about 450 F., and the mixtures thereof suitable as the hydrocarbon base of the composition of the invention will preferably have an ASTM method D 86 distillation range of from about 80 to 100 F. up to about 375 to 425 F.

Besides the ether and phosphorus compound the composition of the invention will preferably contain an antiknock concentration of -a lead antiknock agent, i.e., a lead anti-detonant, such as a tetra-lower-alkyl lead compound, for example tetraethyl lead. In fact the advantages of the presence of the ether and phosphorus compound in a number of the important respects already discussed are of course dependent upon the presence of such a lead antiknock agent. The concentration of the lead antiknock agent is preferably at least 0.5 cc. per gallon and up to 6 cc. per gallon, more especially at least 1 cc. per gallon and no more than 3 cc. per gallon. When a lead antiknock agent is used a halohydrocarbon scavenger such as ethylene dibromide or a mixture of ethylene dibromide and ethylene dichloride is preferably added in conjunction therewith, especially in an amount of from about 1.0 to about 1.5 or 1.6 theories, 1.0 theory being the amount necessary to provide two atoms of halogen per atom of lead in the lead antiknock agent present. Also useful in the composition of the invention are other antiknock agents such as iron carbonyl, dicyclopentadienyl iron, xylidene, N-methylaniline and the organo-manganese compounds of Brown et al., U.S. 2,818,417, especially methylcyclopentadienyl manganese tricarbonyl, or bis(cy- 8 clopentadienyl) manganese. Such compounds are suit ably used either as the only antiknock agent or preferably as a supplemental antiknoc'k agent with for example tetraethyl lead.

Other additives suitably used if desired in the composition of the invention include the various anti-icing agents such as N-C -alkylpropylenediamine and dimethylformamide; combustion chamber deposit modifiers such as glycol esters of boric acid for example isopropyl 2-methyl-2,4-pentanediol borate, 2-methyl-2,4 pentanediol monoacid borate, bis(l,1,3 trimethyl trimethyleneoxy) boric oxide, and the like; anti-oxidants such as N,N'-disecondarybutylphenylenediamine, 2,6 ditertiarybutyl-4- methylphenol, 4,4 methylene bis(2,6 ditertiarybutylphenol), and the like; corrosion inhibitors such as polymerized linoleic acids and N,C-disu-bstiuted imidazolines; metal deactivators such as N,N-disalicyla1-1,2-propanediamine; and dyes, silicone oils, and the like.

Whenever gallons are referred to herein, U.S. gallons are indicated, i.e. 3.7853 liters.

Besides the gasoline compositions described above, an especially suitable example of the composition of the invention is the following:

Petroleum gasoline hydrocarbons 90% v. Diisopropyl ether (the commercial product obtained by reaction of water and propylene described and identified aboveas D 10% v. Tetraethyl lead 2.8 cc./gal. Ethylene dibromide 0.5 theory. Ethylene dichloride 1.0 theory. Tricresyl phosphate 0.3 theory.

(i.e., 0.38%wt.). N-C -alkyl-1,3-propanediamine 30 p.p.m. (Wt.). N,N' disecondarybutylphenylenediamine 0.0005% Wt.

This composition had an ASTM research method octane number of 102.0 (Wiese scale, i.e., isooctane+0.l6 cc. TEL/gal), an ASTM motor method octane number of 92.5, an ASTM distillation of from about 100 F. to about 400 F.

Other suitable examples of the composition of the invention, which may also contain various other minor components as described above, include:

Petroleum gasoline hydrocarbons v. Methyl tertiarybutyl ether 15% v. Tetraethyl lead 3 cc./ gal. Tributyl phosphate 0.2 theory.

Petroleum gasoline hydrocarbons 80% v. Diisopropyl ether 20% v. Tricresyl phosphate 0.02% wt.

Petroleum gasoline hydrocarbons 88% v. Diisopropyl ether 12% v. Tetraethyl lead 2 cc./ gal. Octyl diphenyl phosphate 0.2 theory.

Petroleum gasoline hydrocarbons 95% v. Isopropyl tertiarybutyl ether 5% v. Tetraethyl lead 2.5 cc./gal. Dimethyl xylyl phosphate 0.15 theory.

Petroleum gasoline hydrocarbons 90% v. Diisopropyl ether 10% v. Tetraethyl lead 2.5 cc./ gal. Tributyl phcsphine 0.10 theory.

9 (7 Petroleum gasoline hydrocarbons 91% v. Methyl tertiarybutyl ether 9% v. Tetraethyl lead 2.8 cc./ gal. Tris(2-chloropropyl) thionophosphate 0.1 theory.

Petroleum gasoline hydrocarbons 85% v. Ethyl tertiarybutyl ether 15% v. Tetraethyl lead 3.0 cc./ gal. Methylcyclopentadienyl manganese tricarbonyl 0.1 gram of manganese/ gal. Tricresyl phosphate 0.3 theory.

Petroleum gasoline hydrocarbons 96% v. Diisopropyl ether 4% v. Tetraethyl lead 3 cc./ gal. Tricresyl phosphate 0.4 theory.

Petroleum gasoline hydrocarbons 92% v. Isopropyl tertiaryamyl ether 8% v. Tetraethyl lead 2.4 cc./ gal. Diphenyl cresyl phosphate 0.12 theory.

1) Petroleum gasoline hydrocarbons 85% v. Diisopropyl ether v. Tetraethyl lead 3.0 cc./ gal. Tris(2-propyl) phosphite 0.2 theory.

Petroleum gasoline hydrocarbons 88% v. Diisopropyl ether 12% v. Tetraethyl lead 2.8 cc./ gal. Tris(2-propyl) phosphite 0.1 theory. Tricresyl phosphate 0.1 theory.

Petroleum gasoline hydrocarbons 85% -v. Methyl tertiarybutyl ether 15% v. Tetraethyl lead 2.5 cc./ gal. Tricresyl phosphate 0.3 theory.

Petroleum gasoline hydrocarbons 75% v. Diisopropyl ether v. Tetraethyl lead 2.5 cc./ gal. Dimethyl cresyl phosphate 0.08 theory. Dimethyl xylyl phosphate 0.08 theory.

Petroleum -gasoline hydrocarbons 93% v. Diisopropyl ether 7% v. Tetraethyl lead 2.7 cc./ gal. Tricresyl phosphite 0.3 theory.

We claim as our invention:

1. A gasoline fuel for spark ignition internal combustion engines comprising a major amount of gasoline boiling range hydrocarbons, a minor eifective anti-detonant amount of an organo-lead antiknock agent, at least 2% and up to 50% by volume of a branched chain di-loweralkyl ether containing a single oxygen atom and at least 4 and no more than 8 carbon atoms wherein at least one of the carbon atoms attached to the single oxygen atom is selected from the group consisting of secondary and tertiary carbon atoms, and from about 0.001% to about 0.1% by Weight of a hydrocarbon soluble organic phosphorus compound selected from the group consisting of trihydrocarbyl phosphates, trihydrocarbyl phosphites, and trihydrocarbyl phosphines, each hydrocarbyl group of which is a monovalent organic radical containing from 1 10 to 10 carbon atoms and containing no atoms other than carbon and hydrogen, the concentration of said phosphorus compound being from 0.05 to about 0.6 theory.

2. A gasoline composition in accordance with claim 1, wherein the phosphorus compound is a trihydrocarbyl phosphate.

3. A gasoline composition in accordance with claim 1, wherein the phosphorus compound is a trihydrocarbyl phosphite.

4. A gasoline composition in accordance with claim 1, wherein the phosphorus compound is a trihydrocarbyl phosphine.

5. A gasoline composition in accordance with claim 2, wherein the tnihydnocarbyl phosphate is tricresyl phosphate.

6. A gasoline composition in accordance with claim 2, wherein the trihydnocarbyl phosphate is octyl diphenyl phosphate.

7. A gasoline composition in accordance with claim 2, wherein the trihydrocarbyl phosphate is dimethyl xylyl phosphate.

8. A gasoline composition in accordance with claim 2, wherein the trihydrocarbyl phosphate is diphenyl cresyl phosphate.

9. A gasoline composition in accordance with claim 3, wherein the trihydrocarbyl phosphite is tris(2-propy1) phosp-hite.

10. A gasoline composition in accordance with claim 4, wherein the trihydrocarbyl phosphine is tributyl phosphine.

11. A gasoline fuel for spark ignition internal combustion engines comprising a major amount of gasoline boiling range hydrocarbons, a minor effective anti-detonant amount of tetraethyl lead, from about 2% to about 25% by volume of a branched chain alkyl other selected from the group consisting of diisopropyl ether and methyl tertiarybutyl ether, and from about 0.001% to about 0.1% by weight of a hydrocarbon-soluble organic phosphorus compound selected irom the group consisting of trihydrocarbyl phosphates, trihydrocarbyl phosphites, and trihydrocarbyl phosphines, each hydnocarbyl group of which is a monovalent organic radical containing from 4 to 10 carbon atoms and containing no atoms other than carbon and hydrogen, the theory concentration of said phosphorus compound being from about 0.05 to about 0.6.

12. A gasoline fuel for spark ignition internal combustion engines comprising a major amount of gasoline boiling range hydrocarbons, a minor effective anti-detonant amount of tetraethyl lead, from about 2% to about 25% by volume of diisopropyl ether, and from about 0.001% to about 0.1% by Weight of a hydrocarbon-soluble organic phosporus compound selected from the group consisting of trihydrocarbyl phosphates, trihydrocarbyl phosphites and trihydrocarbyl phosphines, each hydrocarbyl group of which is a monovalent organic radical containing from 4 to 10 carbon atoms and containing no atoms other than carbon and hydrogen, the theory conecentration of said phosphorus compound being from about 0.1 to about 0.4.

13. A gasoline composition in accordance with claim 12, wherein the phosphorus compound is tricresyl phosphate and the concentration thereof is from about 0.01% to about 0.06% by weight.

14. A gasoline composition in accordance with claim 13, wherein the phosphorus compound is tricresyl phosphite and the concentration thereof is from about 0.01% to about 0.06% by weight.

15. A gasoline composition in accordance with claim 13, wherein the phosphorus compound is a mixture of tricresyl phosphate and tris(2-propyl) phosphite and the total concentration thereof is from about 0.01% to about 0.06% by weight.

16. A gasoline composition in accordance with claim 13, wherein the phosphorus compound is a mixture of dimethyl cresyl phosphate and dimethyl xylyl phosphate 1 1 and the tot-a1 concentration thereof is from about 0.01% to about 0.06% by weight.

17. A gasoline composition in accordance with claim 13, wherein the phosphorus compound is ootyl diphenyl phosphate and the concentration thereof is from about 0.01% to about 0.06% by Weight.

References Cited in the file of this patent UNITED STATES PATENTS 1,398,948 Schreiber Nov. 29, 1921 2,046,243 Buc June 30, 1936 2,209,204 -McCulloch ot "a1 July 30, 1940 2,724,719 Markley et a1. Nov. 22, 1955 2,797,153 Bereslavisky June 25, 1957 2,860,958 Gilbert Nov. 18, 1958 2,866,695 Gilbert Dec. 30, 1958 2,897,068 Pellegnini et al. July 28, 1959 OTHER REFERENCES Ind. and Eng. Chem, March 1948, vol. 40, No. 3, Suitability of Gasolines as Fuel, by James et 21., pp. 405-411.

Ind. and Eng. Chem, March 1951, vol. 43, No. 3, Antiknoek Antagonists, by Livingston pp. 663670.

Aviation Gasoline Manufacture by Van Winkle, first ed., 1944, McGraw-Hill Book 00., Inc., pp. 215-216. 

1. A GASOLINE FUEL FOR SPARK IGNITION INTERNAL COMBUSTION ENGINES COMPRISING A MAJOR AMOUNT OF GASOLINE BOILING RANGE HYDROCARBONS, A MINOR EFFECTIVE ANTI-DETONANT AMOUNT OF AN ORGANO-LEAD ANTIKNOCK AGENT, AT LEAST 2% AND UP TO 50% BY VOLUME OF A BRANCHED CHAIN DI-LOWERALKYL ETHER CONTAINING A SINGLE OXYGEN ATOM AND AT LEAST 4 AND NO MORE THAN 8 CARBON ATOMS WHEREIN AT LEAST ONE OF THE CARBON ATOMS ATTACHED TO THE SINGLE OXYGEN ATOM IS SELECTED FROM THE GROUP CONSISTING OF SECONDARY AND TERTIARY CARBON ATOMS, AND FROM ABOUT 0.001% TO ABOUT 0.1% BY WEIGHT OF A HYDROCARBON SOLUBLE ORGANIC PHOSPHORUS COMPOUND SELECTED FROM THE GROUP CONSISTING OF TRIHYDROCARBYL PHOSPHATES, TRIHYDROCARBYL PHOSPHITES, AND TRIHYDROCARBYL PHOSPHINE, EACH HYDROCARBYL GROUP OF WHICH IS A MONOVALENT ORGANIC RADICAL CONTAINING FROM 1 TO 10 CARBON ATOMS AND CONTAINING NO ATOMS OTHER THAN CARBON AND HYDROGEN, THE CONCENTRATION OF SAID PHOSPHORUS COMPOUND BEING FROM 0.05 TO ABOUT 0.6 THEORY. 